Enabling phase tracking for a communication device

• US 10,057,026 B2
• Filed: 03/14/2016
• Issued: 08/21/2018
• Est. Priority Date: 12/07/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Jones, IV, Vincent Knowles, Sampath, Hemanth, Van Nee, Didier Johannes Richard
• Primary Examiner(s): Nawaz, Asad
• Assistant Examiner(s): Waqas, Saad A
• Application Number:
  US15/069,748
• Publication Number:
  US 20160197710A1
• Time in Patent Office: 890 Days
• Field of Search: 370329
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

A communication device for enabling phase tracking is described. The communication device includes a processor and instructions stored in memory. The communication device generates a plurality of pilot symbols. The pilot symbols conform to a rank-deficient pilot mapping matrix. The communication device also transmits the plurality of pilot symbols.

Claims

1. A communication device for enabling phase tracking, comprising:

a processor;

memory in electronic communication with the processor;

instructions stored in the memory, the instructions being executable to;

generate a sequence of Orthogonal Frequency-Division Multiplexing (OFDM) pilot symbols for each of a plurality of spatial streams, wherein the sequences of OFDM pilot symbols for the plurality of spatial streams comprise a rank-deficient pilot mapping matrix with at least one pair of identical OFDM pilot symbol sets, wherein the rank-deficient pilot mapping matrix has a number of linearly independent rows or columns less than a smallest dimension of a pilot mapping matrix; and

send each sequence of OFDM pilot symbols on a corresponding spatial stream during a training period.

2. The communication device of claim 1, wherein the instructions are further executable to send data to a base station.

3. The communication device of claim 1, wherein the rank-deficient pilot mapping matrix is a rank-deficient pilot mapping matrix R, wherein each row corresponds to OFDM pilot symbols transmitted on a different spatial stream and each column corresponds to OFDM pilot symbols transmitted on different OFDM symbols.

4. The communication device of claim 1, wherein the rank-deficient pilot mapping matrix for four spatial streams and four OFDM symbols is

5. The communication device of claim 1, wherein the rank-deficient pilot mapping matrix for six spatial streams and six OFDM symbols is

6. The communication device of claim 1, wherein the rank-deficient pilot mapping matrix for eight spatial streams and eight OFDM symbols is

7. The communication device of claim 1, wherein the training period comprises Very High Throughput-Long Training Field (VHT-LTF) symbols transmitted according to Institute of Electrical and Electronics Engineers (IEEE) 802.11ac specifications.

8. The communication device of claim 1, wherein the OFDM pilot symbols are transmitted on tones reserved for pilot tones in Very High Throughput-Long Training Fields (VHT-LTFs).

9. A communication device for tracking phase, comprising:

a processor;

memory in electronic communication with the processor;

instructions stored in the memory, the instructions being executable to;

receive during a training period a sequence of Orthogonal Frequency-Division Multiplexing (OFDM) pilot symbols on each of a plurality of spatial streams, wherein the sequences of OFDM pilot symbols for the plurality of spatial streams comprise a rank-deficient pilot mapping matrix with at least one pair of identical OFDM pilot symbol sets, wherein the rank-deficient pilot mapping matrix has a number of linearly independent rows or columns less than a smallest dimension of a pilot mapping matrix; and

determine a phase estimate based on the at least one pair of identical OFDM pilot symbol sets.

10. The communication device of claim 9, further comprising instructions executable to:

estimate a channel based on the phase estimate; and

demodulate and/or decode received OFDM symbols based on the channel estimate.

11. The communication device of claim 9, wherein the rank-deficient pilot mapping matrix is a rank-deficient pilot mapping matrix R, wherein each row corresponds to OFDM pilot symbols transmitted on a different spatial stream and each column corresponds to OFDM pilot symbols transmitted on different OFDM symbols.

12. The communication device of claim 9, wherein determining the phase estimate comprises computing a cross-correlation of the at least one pair of identical OFDM pilot symbol sets.

13. The communication device of claim 9, wherein determining the phase estimate comprises computing a phase delta of the at least one pair of identical OFDM pilot symbol sets.

14. The communication device of claim 9, wherein the training period comprises Very High Throughput-Long Training Field (VHT-LTF) symbols transmitted according to Institute of Electrical and Electronics Engineers (IEEE) 802.11ac specifications.

15. A method for enabling phase tracking, comprising:

generating, on a communication device, a sequence of Orthogonal Frequency-Division Multiplexing (OFDM) pilot symbols for each of a plurality of spatial streams, wherein the sequences of OFDM pilot symbols for the plurality of spatial streams comprise a rank-deficient pilot mapping matrix with at least one pair of identical OFDM pilot symbol sets, wherein the rank-deficient pilot mapping matrix has a number of linearly independent rows or columns less than a smallest dimension of a pilot mapping matrix; and

sending each sequence of OFDM pilot symbols on a corresponding spatial stream during a training period.

16. The method of claim 15, further comprising sending data to a base station.

17. The method of claim 15, wherein the rank-deficient pilot mapping matrix is a rank-deficient pilot mapping matrix R, wherein each row corresponds to OFDM pilot symbols transmitted on a different spatial stream and each column corresponds to OFDM pilot symbols transmitted on different OFDM symbols.

18. The method of claim 15, wherein the rank-deficient pilot mapping matrix for four spatial streams and four OFDM symbols is

19. The method of claim 15, wherein the rank-deficient pilot mapping matrix for six spatial streams and six OFDM symbols is

20. The method of claim 15, wherein the rank-deficient pilot mapping matrix for eight spatial streams and eight OFDM symbols is

21. The method of claim 15, wherein the training period comprises Very High Throughput-Long Training Field (VHT-LTF) symbols transmitted according to Institute of Electrical and Electronics Engineers (IEEE) 802.11ac specifications.

22. The method of claim 15, wherein the sequence of OFDM pilot symbols are transmitted on tones reserved for pilot tones in Very High Throughput-Long Training Fields (VHT-LTFs).

23. A method for tracking phase, comprising:

receiving, by a communication device and during a training period, a sequence of Orthogonal Frequency-Division Multiplexing (OFDM) pilot symbols on each of a plurality of spatial streams, wherein the sequences of OFDM pilot symbols for the plurality of spatial streams comprise a rank-deficient pilot mapping matrix with at least one pair of identical OFDM pilot symbol sets, wherein the rank-deficient pilot mapping matrix has a number of linearly independent rows or columns less than a smallest dimension of a pilot mapping matrix; and

determining a phase estimate based on the at least one pair of identical OFDM pilot symbol sets.

24. The method of claim 23, further comprising:

estimating a channel based on the phase estimate; and

demodulating and/or decoding received OFDM symbols based on the channel estimate.

25. The method of claim 23, wherein the rank-deficient pilot mapping matrix is a rank-deficient pilot mapping matrix R, wherein each row corresponds to OFDM pilot symbols transmitted on a different spatial stream and each column corresponds to OFDM pilot symbols transmitted on different OFDM symbols.

26. The method of claim 23, wherein determining the phase estimate comprises computing a cross-correlation of the at least one pair of identical OFDM pilot symbol sets.

27. The method of claim 23, wherein determining the phase estimate comprises computing a phase delta of the at least one pair of identical OFDM pilot symbol sets.

28. The method of claim 23, wherein the training period comprises Very High Throughput-Long Training Field (VHT-LTF) symbols transmitted according to Institute of Electrical and Electronics Engineers (IEEE) 802.11ac specifications.

29. A non-transitory computer-readable medium having instructions thereon, the instructions comprising:

code for causing a communication device to generate a sequence of Orthogonal Frequency-Division Multiplexing (OFDM) pilot symbols for each of a plurality of spatial streams, wherein the sequences of OFDM pilot symbols for the plurality of spatial streams comprise a rank-deficient pilot mapping matrix with at least one pair of identical OFDM pilot symbol sets, wherein the rank-deficient pilot mapping matrix has a number of linearly independent rows or columns less than a smallest dimension of a pilot mapping matrix; and

code for causing a communication device to send each sequence of OFDM pilot symbols on a corresponding spatial stream during a training period.

30. A non-transitory computer-readable medium having instructions thereon, the instructions comprising:

code for causing a communication device to receive during a training period a sequence of Orthogonal Frequency-Division Multiplexing (OFDM) pilot symbols on each of a plurality of spatial streams, wherein the sequences of OFDM pilot symbols for the plurality of spatial streams comprise a rank-deficient pilot mapping matrix with at least one pair of identical OFDM pilot symbol sets, wherein the rank-deficient pilot mapping matrix has a number of linearly independent rows or columns less than a smallest dimension of a pilot mapping matrix; and

code for causing a communication device to determine a phase estimate based on the at least one pair of identical OFDM pilot symbol sets.

31. An apparatus for enabling phase tracking, comprising:

means for generating a sequence of Orthogonal Frequency-Division Multiplexing (OFDM) pilot symbols for each of a plurality of spatial streams, wherein the sequences of OFDM pilot symbols for the plurality of spatial streams comprise a rank-deficient pilot mapping matrix with at least one pair of identical OFDM pilot symbol sets, wherein the rank-deficient pilot mapping matrix has a number of linearly independent rows or columns less than a smallest dimension of a pilot mapping matrix; and

means for sending each sequence of OFDM pilot symbols on a corresponding spatial stream during a training period.

32. An apparatus for tracking phase, comprising:

means for receiving during a training period a sequence of Orthogonal Frequency-Division Multiplexing (OFDM) pilot symbols on each of a plurality of spatial streams, wherein the sequences of OFDM pilot symbols for the plurality of spatial streams comprise a rank-deficient pilot mapping matrix with at least one pair of identical OFDM pilot symbol sets, wherein the rank-deficient pilot mapping matrix has a number of linearly independent rows or columns less than a smallest dimension of a pilot mapping matrix; and

means for determining a phase estimate based on the at least one pair of identical OFDM pilot symbol sets.